Reactor for producing a product gas from a fuel

Abstract

Method and reactor for producing a product gas from a fuel. The fuel is input into a pyrolysis chamber (6) and a pyrolysis process is executed for obtaining a product gas. Parts of the fuel exiting from the pyrolysis chamber (6) are recirculated to a combustion chamber (20, 23). In the combustion chamber (20, 23) a gasification process is executed in a fluidized bed (20) using a primary process fluid, followed by a combustion process in an area (23) above the fluidized bed (20) using a secondary process fluid.

The invention claimed is: 
     
       1. Method for producing a product gas from a fuel, comprising
 inputting a fuel into a pyrolysis chamber and executing a pyrolysis process for obtaining a product gas from volatile constituents of the fuel, 
 recirculating solid parts of the fuel exiting from the pyrolysis chamber to a combustion chamber, and 
 in the combustion chamber executing a gasification process for the recirculating solid parts in a gasification zone accommodating a fluidized bed using a primary process fluid, wherein the gasification process is controlled by controlling a velocity and oxygen content of the primary process fluid, and wherein a combustion process is controlled by controlling a velocity and oxygen content of a secondary process fluid, followed by the combustion process in an area above the gasification zone accommodating the fluidized bed using the secondary process fluid, wherein the gasification process is operated with an equivalence ratio ER between 0.9 and 0.99, the equivalence ratio ER being defined as the ratio of the amount of oxygen supplied divided by the amount of oxygen needed for complete combustion of the solid parts of the fuel supplied in the gasification zone, and 
 wherein controlling the velocity and oxygen content of the primary process fluid and the secondary process fluid comprise increasing or decreasing the velocity and the oxygen content. 
 
     
     
       2. Method according to  claim 1 , wherein the gasification zone accommodating the fluidized bed is operated with an equivalence ratio ER of 0.99. 
     
     
       3. Method according to  claim 1 , wherein the primary process fluid is used for controlling a temperature in the fluidized bed. 
     
     
       4. Method according to  claim 1 , wherein the gasification process is controlled by one or more of:
 reducing supply of the primary process fluid, reducing oxygen content in the primary process fluid, adding an inert gas to the primary process fluid, and/or adding a flue gas from the combustion process to the primary process fluid. 
 
     
     
       5. Method according to  claim 4 , wherein the gasification process is controlled based on measurement of a temperature in the product gas from the pyrolysis process. 
     
     
       6. Method according to  claim 4 , wherein the gasification process is controlled based on a temperature of the flue gas from the combustion process. 
     
     
       7. Method according to  claim 4 , wherein the gasification process is controlled based on an oxygen content in the flue gas from the combustion process.